The cAMP receptor protein (CRP) plays a key role in transcription as a positive regulatory element via cAMP dependent DNA binding. The proposed research will investigate the role of CRP structure and function for cAMP and DNA binding as follows: Role of C-termini in DNA binding; Effect of cNMP in stability of CRP and alpha CRP (cAMP binding core); Role of SH and lysyl groups; Photoaffinity labeling of cAMP binding site; Isolation of DNA binding region of CRP and reconstitution using alpha CRP.